ECMlink Lean tip-in off Idle

[Nate355RS]

1). Any boost, vac, or exhaust leaks?
None

2). Verified mechanical timing?
Yes
3). Verified base timing?
Yes
4). Ignition system
COP BR7es
5). Motor health (Compression Test)
Cylinder 1: 180
Cylinder 2: 185
Cylinder 3: 180
Cylinder 4: 180

6). Performed basic throttle body adjustments?
Yes
7). Compression ratio

8). Any known bad sensors or brittle wiring?
No
9). Any DTC/CEL codes?
No
10). Electrical system
Car off (not running):
Car running:

11). Base fuel pressure and injector values
Base Fuel Pressure: 44psi
Injector Size (cc/min): 1050cc

12). Properly calibrated and configured wideband sensor
Sensor Brand: LC2
Calibration Date: Today

13). Type of fuel
Type: 93
Percent of Ethanol:

14). Watched ECMlink how-to videos? Yes

I'm fighting a lean condition when I touch the throttle off idle. I have ISCPosition, AirflowPerRev, and the AFRs dialed in pretty good but can't seem to shake this lean stumble. The car cruises great, makes power, will hold a solid idle, but give it a little gas off idle and it goes lean and usually dies if I don't keep my foot on the gas.

In the log, you can see I give it throttle and the car stalls. I then I increase deadtime to 330 and start it up, it idles rich but it won't stall and it revs smooth off idle. I don't really want to run idle that rich, any ideas how to fix this?

Any ideas?

 

[19gsx91]

What BOV are you using? I had the same issue with an over crushed 1g BOV, switched to a non crushed and it cured it.

 

[Nate355RS]

It's a Tial, only has a handful of miles on it from extremepsi

 

[1990TSIAWDTALON]

Richen it up in the base tip in. If it doesnt react in some way you can always put it back...(take a picture . )
If its worse then lean base tip in out, maybe your over squirting it.

 

[Nate355RS]

Funny you mention over squirting, I was just reading this http://www.dsmtuners.com/threads/li...ual-attached-log.436795/page-5#post-152992985

I have my LC2 in the downpipe, and in the log it spikes lean then goes pig rich. Maybe the lean spike isn't the actual AFR. When it stumbles and boggs more throttle keeps it alive, so maybe it is rich? Ugh, I've been reading about thus stuff too much today. I'll have to play with it tomorrow.

 

[1990TSIAWDTALON]

Nate, you just said it. PLAY with it, you can always put things back. Don't get frustrated. I like playing with mine just to see what happens. If you still are stumped, ask the guru's on Ecmlink's forum, they have been helpful to me. We have some good tuners on here so I hope I see someone jump in with more help.

 

[Nate355RS]

I played with it some more. I first decreased BaseTipInTPSAdj down to 0 for the 0-1 rows, thinking maybe it's actually getting too much fuel. No help. Then I incrementally increased BaseTipInTPSAdj all the way up to 30 and it didn't help idle tip in at all. So I put those values back to stock and moved on to CoolantTempFuelAdj and played with the 176* and 190* cells. I increased those one point at a time until it matched the cold start values, that didn't help either so I reset them back to stock values

I figured it couldn't hurt to run another BLT, so I took it up to 30psi and it held pressure like a champ. I also grounded timing connector and diagnostic pin, checked base timing, set BISS to target idle, checked base timing again, ungrounded the pins, asjusted BISS so ISCPosition was 30. Still no joy.

To get the car driveable I upped the global deadtime to 330 and it cures my lean stumble off idle, but idle runs rich. Closed loop LTFT gets the idle close to stoich, but still stalls sometimes when coming to a stop or after a sharp rev. So it's only a bandaid fix. On the brightside it's flowing over 40lbs/min now

One thing I did notice was my LrndIdleAdj seems frozen at 176, no matter the BISS position. So far that's the only lead I have so I'm off to reading about LrndIdleAdj.

 

[Nate355RS]

Found the issue. I copied the DA timing table from a tune I had on a stock 6 bolt that ran great and was tunned by a pro. It had about 15* of timing at idle. Seemed excessive to me so I backed the idle timing cells to a stock 8* and it idles great now. No more lean tip in and I can run the correct deadtime.

 

[1990TSIAWDTALON]

Nate, what deadtime did you end up with on those injectors? Glad you found the problem, I knew you would and thanks for posting back the results to help everyone!

 

[Nate355RS]

I got the best idle and part throttle response with the deadtime at 275. A deadtime of 220 put the WB readings dead on, but I still found the occasional stall after a free rev or coasting to a stop. So I bumped the deadtime up until I couldn't stall the car if I tried.

Just a note: I've learned to NOT fully trust my WBO2 at idle. Widebands assume 100% of the exhaust was involved in the combustion process. So factors that let unburnt intake air escape through the exhaust valve makes WBs inherently inaccurate. Since I increased overlap and ran 15* timing at idle, I was just chasing my tail trying to get the WB readings inline.

 

[1990TSIAWDTALON]

Good deal. I will be changing injectors real soon and bumping up to 1800's so I will be going thru the whole process again myself. Thanks for the insite!!